diff --git a/server/src/index.ts b/server/src/index.ts
index c9c0300..07c0e8d 100644
--- a/server/src/index.ts
+++ b/server/src/index.ts
@@ -339,6 +339,30 @@ app.post('/api/play', async (req: Request, res: Response) => {
   }
 });
 
+// Lautstärke zur Laufzeit ändern (0..1). Wirken sofort auf aktuelle Resource, sonst als Default für nächste Wiedergabe.
+app.post('/api/volume', (req: Request, res: Response) => {
+  try {
+    const { guildId, volume } = req.body as { guildId?: string; volume?: number };
+    if (!guildId || typeof volume !== 'number' || !Number.isFinite(volume)) {
+      return res.status(400).json({ error: 'guildId und volume (0..1) erforderlich' });
+    }
+    const safeVolume = Math.max(0, Math.min(1, volume));
+    const state = guildAudioState.get(guildId);
+    if (!state) {
+      return res.status(404).json({ error: 'Kein Voice-State für diese Guild' });
+    }
+    state.currentVolume = safeVolume;
+    if (state.currentResource?.volume) {
+      state.currentResource.volume.setVolume(safeVolume);
+      console.log(`${new Date().toISOString()} | live setVolume(${safeVolume}) guild=${guildId}`);
+    }
+    return res.json({ ok: true, volume: safeVolume });
+  } catch (e: any) {
+    console.error('Volume-Fehler:', e);
+    return res.status(500).json({ error: e?.message ?? 'Unbekannter Fehler' });
+  }
+});
+
 // Static Frontend ausliefern (Vite build)
 const webDistPath = path.resolve(__dirname, '../../web/dist');
 if (fs.existsSync(webDistPath)) {
diff --git a/web/src/App.tsx b/web/src/App.tsx
index f1dda88..e0294e2 100644
--- a/web/src/App.tsx
+++ b/web/src/App.tsx
@@ -1,5 +1,5 @@
 import React, { useEffect, useMemo, useState } from 'react';
-import { fetchChannels, fetchSounds, playSound } from './api';
+import { fetchChannels, fetchSounds, playSound, setVolumeLive } from './api';
 import type { VoiceChannelInfo, Sound } from './types';
 
 export default function App() {
@@ -88,7 +88,14 @@ export default function App() {
             max={1}
             step={0.01}
             value={volume}
-            onChange={(e) => setVolume(parseFloat(e.target.value))}
+            onChange={async (e) => {
+              const v = parseFloat(e.target.value);
+              setVolume(v);
+              if (selected) {
+                const [guildId] = selected.split(':');
+                try { await setVolumeLive(guildId, v); } catch {}
+              }
+            }}
             aria-label="Lautstärke"
           />
         </div>
diff --git a/web/src/api.ts b/web/src/api.ts
index f6ab2fd..a9c8539 100644
--- a/web/src/api.ts
+++ b/web/src/api.ts
@@ -28,6 +28,18 @@ export async function playSound(soundName: string, guildId: string, channelId: s
   }
 }
 
+export async function setVolumeLive(guildId: string, volume: number): Promise<void> {
+  const res = await fetch(`${API_BASE}/volume`, {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({ guildId, volume })
+  });
+  if (!res.ok) {
+    const data = await res.json().catch(() => ({}));
+    throw new Error(data?.error || 'Volume ändern fehlgeschlagen');
+  }
+}
+